1. Field of the Invention
This invention relates to an improved apparatus for recording across the width of a relatively wide strip of electro-sensitive paper or other similar web material having a conductive coating thereon; and, more particularly, to a novel recorder which has a stationary, multiple-pin electric discharge recording head.
2. Description of the Prior Art
Electro-sensitive recorders are well known in the art. In one prior art electro-sensitive recorder of the class to which this invention particularly applies, a paper having a thin conductive coating (aluminum, for example) on one of its surfaces is driven past a recording head which contacts the coating. The prior art recording head comprises one or more discrete pins which are configured so that each pin makes point contact with the conductive coating on the paper. The conductive coating on the paper is electrically connected to one terminal of a potential source and when the other terminal is momentarily connected to a particular pin, a voltage gradient produced at the point where the pin contacts the coating removes a small region of the conducting coating exposing a dark undercoating and, thusly, records a mark.
Multistylus structures are used in the prior art for the print head, e.g., a plurality of separate print wires embedded in a monolithic support such as those shown in U.S. Pat. Nos. 3,381,300; 3,521,293; a plurality of electrodes formed on a printed circuit board such as those shown in U.S. Pat. Nos. 3,267,485; 3,470,563; 3,618,115; 3,618,118; 3,381,300; 3,521,293; 3,702,001; 3,733,613; 3,702,001; and 3,733,613. These prior art print heads are used in various non-impact electrographic printing operations such as electrostatic, electrolytic, spark recording, etc. One usual method of construction of the prior art multistylus head array for such electrographic recording involves the accurate placement of a plurality of small diameter wires in a technique requiring elaborate fixtures and other locating devices to provide adequate final construction tolerances.
In prior art electro-sensitive recorders, the pin or pins tend to become fouled with a residue produced by the recording process. Pin fouling is not a particularly severe problem in recorders in which the head moves in order to record across the entire width of the paper as the motion of the head tends to mechanically clean it. However, fouling is a severe problem if the head is stationary. The problem is particularly severe with a stationary head having a large number of pins.